A glycopeptide antibiotic is an antibiotic having a complicated polycyclic peptide structure which is produced by a variety of microorganisms, and is provided as an antibacterial agent effective for most of Gram-positive bacteria. In recent years, penicillin and cephalosporin resistant bacteria have appeared, and infection with multidrug resistant bacteria and methicillin-resistant Staphylococcus aureus (MRSA) lead to important problems in the medical field. A glycopeptide-based antibiotic such as vancomycin is typically effective for such microorganisms, and vancomycin has become the last resort drug for infection with MRSA and other resistant bacteria. However, particular microorganism such as vancomycin-resistant Enterococci (VRE) have begun to obtain resistance to vancomycin. In addition, recently, Staphylococcus aureus (VRSA) which has acquired VRE resistance has been found out.
Vancomycin has a structure represented by the following formula:
more specifically, the following formula:
and the aromatic ring of amino acid residues which are the second and sixth position from N-terminal is substituted with a chlorine atom. Vancomycin derivatives are generally also termed glycopeptide antibiotics and, more academically, a generic name of dalbaheptides derived from D-alanyl-D-alanine binding antibiotics with a heptapeptidic structure has been proposed. The dalbaheptide has a peptide chain consisting of seven amino acids including aromatic amino acids as a common fundamental skeleton.
Previously, vancomycin, and other glycopeptide antibiotics having these common peptide chain as fundamental skeleton have been variously modified. For example, chloroorienticin B having the following structure (Patent Literature 1: JP-A No. 1-240196) and derivatives thereof (Patent Literature 2: JP-A No. 2001-163898) are known.
(wherein R5 is hydrogen, glucosyl, or (4-epi-vancosaminyl)-O-glucosyl)
As other glycopeptide antibiotics, for example, the following compounds are known.

In addition, glycopeptide compounds in which the amino sugar of vancomycin is modified are also known (e.g., Patent Literature 18).
However, development of antibacterial agents with novel structure in which antibacterial activity to drug-resistant bacteria, water solubility, distribution, safety and the like are further improved is desired.
On the other hand, as methods of chemically modifying glycopeptide antibiotics, methods using various glycosylase have been reported (e.g., Patent Literature 3, Non-Patent Literatures 1 to 5).
In addition, a glycopeptide compounds in which a sugar side chain consisting of 1 or 2 sugars, to which an aminomethylene-type substituent is bound, is bound to the aromatic ring part of the fourth amino acid residue of the glycopeptide antibiotic are known (e.g., Patent Literatures 4 to 17, Non-Patent Literatures 5 to 17).
Among them, in Non-Patent Literature 11 (Angewandte Chemie, International Edition (2003), 42(38), 4657-4660), a vancomycin derivative in which —CH2 NH2 is bound to galactose at the sugar chain terminal is described, but no compound in which the amino group is further chemically modified is described.
In addition, recent trend of study regarding glycopeptide compounds has been reported (e.g., Non-Patent Literature 18)    [Patent Literature 1] JP-A No. 1-240196    [Patent Literature 2] JP-A No. 2001-163898    [Patent Literature 3] WO2006003456    [Patent Literature 4] US2005239689A1    [Patent Literature 5] US2003068669A1    [Patent Literature 6] US2004259228A1    [Patent Literature 7] US2005266523A1    [Patent Literature 8] WO2004019970    [Patent Literature 9] WO2001081373    [Patent Literature 10] WO2001081372    [Patent Literature 11] WO2000069893    [Patent Literature 12] WO2000059528    [Patent Literature 13] WO2000042067    [Patent Literature 14] WO2000004044    [Patent Literature 15] WO9303060    [Patent Literature 16] EP301785A1    [Patent Literature 17] EP273727A1    [Patent Literature 18] WO2006057303    [Non-Patent Literature 1] Journal of the American Chemical Society (2005), 127(30), 10747-10752    [Non-Patent Literature 2] Proceedings of the National Academy of Sciences of the United States of America (2004), 101(13), 4390-4395    [Non-Patent Literature 3] Chemistry—An Asian Journal (2006), 1, 445-452    [Non-Patent Literature 4] Current Opinion in Biotechnology 2005, 16:622-630    [Non-Patent Literature 5] Nature Biotechnology (2003), 21(12), 1467-1469    [Non-Patent Literature 6] ACS Chemical Biology (2006), 1(8), 499-504    [Non-Patent Literature 7] Activity Research (2006), 72(1) 20-33    [Non-Patent Literature 8] Bioorganic & Medical Chemistry Letters (2005), 15(16), 3801-3805    [Non-Patent Literature 9] Organic Letters (2005), 7(8), 1513-1515    [Non-Patent Literature 10] Chemistry & Biology (2005), 12(1), 131-140    [Non-Patent Literature 11] Angewandte Chemie, International, Edition (2003), 42(38), 4657-4660    [Non-Patent Literature 12] Journal of Medicinal Chemistry (2003), 46(13), 2755-2764    [Non-Patent Literature 13] Tetrahedron (2002), 58(32), 6585-6594    [Non-Patent Literature 14] Bioorganic & Medicinal Chemistry Letters (2002), 12(6), 849-852    [Non-Patent Literature 15] Chemistry—A European Journal (2001), 7(17), 3798-3823    [Non-Patent Literature 16] Journal of the American Chemical Society (2000), 122(50), 12608-12609    [Non-Patent Literature 17] Journal of Antibiotics (1998), 51(5), 525-527    [Non-Patent Literature 18] Expert Opinion on Therapeutic Patents (2004) 14(2) 141-173